Gear unit having a first and a second housing part

ABSTRACT

A gear unit is described as having a first and a second housing part, an intermediate shaft of the gear unit being mounted via two bearings in a bushing accommodating the bearings, the bushing centering the first housing part against the second housing part.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/390,654, which is the national stage of PCT/EP2013/000643,having an international filing date of Mar. 6, 2013, and claims priorityto Application No. 102012006790.9, filed in the Federal Republic ofGermany on Apr. 4, 2012, each of which is expressly incorporated hereinin its entirety by reference thereto.

FIELD OF THE INVENTION

The present invention relates to a gear unit having a first and a secondhousing part.

BACKGROUND INFORMATION

It is generally known that intermediate shafts of gear units are mountedvia bearings in the gear housing.

SUMMARY

Therefore, the object of the present invention is to further develop agear unit, in doing which, the intention being for its manufacture to besimple.

The objective is achieved according to the present invention in the gearunit.

Important features of the present invention with regard to the gear unithaving a first and a second housing part are that an intermediate shaftof the gear unit is mounted via two bearings in a bushing accommodatingthe bearings,

the bushing centering the first housing part against the second housingpart.

The advantage in this context is that the bearings together with theintermediate shaft are able to be mounted in the bushing, and the entireunit thus assembled is then able to be inserted and pressed into thefirst housing part. The second housing part is thereupon slipped ontothe bushing projecting partially from the first housing part. In thismanner, the two housing parts are able to be centered against eachother, and at the same time, assembly is simplified. The housing partsmay be produced easily as die casting.

The bushing may be produced as a die-cast part, especially when made ofmetal, or as an injection-molded part, especially when made of plastic.

Incorrect assembly is easily preventable owing to the symmetricalconstruction of the bushing. In this context, the plane of symmetrycontains the center of mass of the bushing, and the axial direction ofthe intermediate shaft is the direction of surface normal with respectto the plane of symmetry.

In one advantageous development, the first and second housing parts arescrew-connected to each other, the screw connection being locatedoutside of the bushing. The advantage here is that a firm connection isable to be produced.

In one advantageous refinement, the bushing has an outer sleeve sectionwhich abuts against the accommodation areas of the two housing parts.This is advantageous because a structure able to support load isattained accompanied by low expenditure for materials, and in addition,openings are provided for the passage of oil.

In one advantageous development, the outer sleeve section has a firstaxial part in the form of an insertion-fit area, and has a second axialpart in the form of an interference-fit area,

the axial direction corresponding to the axis of the intermediate shaft.This offers the advantage that insertion into the housing parts isfacilitated, and the interference-fit area is able to support load owingespecially to thermal shrinking. In addition, adhesive agent isprovided.

In one advantageous refinement, the bushing has an inner sleeve sectionwhich accommodates a first bearing of the intermediate shaft in a firstaxial part, and a second bearing of the intermediate shaft in a secondaxial part, a crosspiece segment being disposed axially between thefirst and second parts whose smallest radial distance is less than thesmallest radial distance of the first or second part. The advantage isthat a structure able to support load is obtained, having axialthrough-openings.

In one advantageous refinement, the inner and outer sleeve sections arejoined via support ribs, the support ribs being set apart from eachother, in particular, being evenly spaced from each other in thecircumferential direction. The advantage in this case is that axialthrough-openings are able to be provided for the passage of oil, andthus for the lubrication of the gear teeth and bearings disposed on bothsides of the bushing.

In one advantageous development, the bearings are tapered rollerbearings, especially in O-configuration, X-configuration or tandemconfiguration. This is advantageous because it permits the use of easilyproducible bearing configurations.

In one advantageous embodiment, the intermediate shaft is joined inrotatably fixed manner to a first toothing part or has a correspondingtoothing, so that a first axial bearing is bounded axially by thetoothing part or the toothing section,

on the axial side of the bushing opposite from this, a further toothingpart being joined in rotatably fixed manner to the intermediate shaftand bounding the other bearing axially, in particular, the furthertoothing part being bounded axially by a retaining ring. The advantagein this context is that preloading of the bearings is easily attainable.

In one advantageous development, the intermediate shaft is provided withor joined in rotatably fixed manner to a bevel-pinion toothing and/orthe intermediate shaft is provided with or joined to a helicalcylindrical-gear toothing. This offers the advantage that theintermediate shaft is able to be manufactured in an easy manner.

In one advantageous embodiment, the bevel-pinion toothing is in meshwith a bevel-gear wheel mounted in the second housing part via bearingsaccommodated there. The advantage in this case is that the bushingadvantageously permits a simple construction of a bevel gear.

In one advantageous development, the first housing part is joined to amotor housing, a rotor shaft being mounted via bearings accommodated inthe motor housing, the rotor shaft being joined in rotatably fixedfashion to an input toothing part of the gear unit, the input toothingpart being surrounded radially by the first housing part. The advantagein this case is that the input toothing part is disposed in the gearunit and is supported via the motor.

In one advantageous embodiment, the toothing part joined in rotatablyfixed manner to the intermediate shaft engages with the input toothingpart joined to the rotor shaft. This offers the advantage that the inputtoothing part is able to be supported via the electric motor.

In one advantageous development, the bushing is pressed into anaccommodation area of the first housing part and into an accommodationarea—situated coaxially relative to it—of the second housing part. Thisis advantageous because centering is able to be realized with the aid ofthe bushing.

In one advantageous refinement, the first and second housing parts areimperviously joined. The advantage in so doing is that oil is able to beused in the interior of the gear unit.

In one advantageous embodiment, an annular spatial area for receivingadhesive is located between one of the housing parts and the bushing,

in particular, the spatial area being delimited by a depression in thebushing and by the accommodation area of the housing part for thebushing. The advantage in this case is that the bushing is able to beprotected against twisting relative to the housing with the aid of theadhesive connection, although upon assembly, the bushing is able torotate prior to the hardening of the adhesive, and thus setting of thebearings is able to be promoted.

Further advantages are derived from the dependent claims. The presentinvention is not limited to the feature combination of the claims.Further useful combination possibilities of claims and/or individualclaim features and/or features of the specification and/or of thefigures are apparent for one skilled in the art, particularly from theproblem definition and/or the objective set by comparison with therelated art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional view through a gear unit according to thepresent invention having a bushing 11.

FIG. 2 shows bushing 11 in an oblique view.

FIG. 3 shows bushing 11 in plan view.

FIG. 4 shows bushing 11 in sectional view.

DETAILED DESCRIPTION

The housing of the gear unit has at least two housing parts 12, 14,which are centered relative to each other by bushing 11.

Bushing 11 accommodates two bearings 8, 10, via which an intermediateshaft 18 is mounted that, at its axial end area on the input side, isjoined in rotatably fixed manner to a gear wheel 20, which is in meshwith an input gear wheel 16 that is joined in rotatably fixed manner toan input shaft 17, especially a rotor of a driving electric motor, notshown. Gear wheel 16, together with shaft 17, is supported in thehousing of the driving device, especially electric motor. The housing ofthe driving device is joined to first housing part 12, a centeringmeans, especially a centering collar, being formed here on first housingpart 12.

At its other axial end area, intermediate shaft 18 is joined inrotatably fixed manner to bevel pinion 9. Alternatively, intermediateshaft 18 is realized in one piece with bevel pinion 9, so that the gearteeth of the bevel pinion are Incorporated in a section of intermediateshaft 18.

Bevel pinion 9 is in mesh with bevel-gear wheel 13, which is supportedvia bearings in second housing part 14 or in a housing part joined tosecond housing part 14.

The inner ring of first bearing 10 of bushing 11 abuts against a shaftoffset, especially against a collar, of intermediate shaft 18.

The outer ring of first bearing 10 abuts against an inner step of theinner wall of bushing 11.

The outer ring of second bearing 8 likewise abuts against an inner stepof the inner wall of bushing 11. In this context, the two inner stepsindicated are formed by a radially inwards extending, ring-shapedsegment located on the inner wall of bushing 11, the segment being setapart radially from intermediate shaft 18.

The inner ring of second bearing 8 abuts against gear wheel 20, whichcooperates with a retaining ring 19 disposed on the side of gear wheel20 facing away from bearing 8.

Thus, by way of example, bearings 8, 10 may be implemented as taperedroller bearings and are retained so as to be bounded axially.

In the case of a two-piece construction of bevel pinion 9 andintermediate shaft 18, an axial limiting means is disposed between bevelpinion 9 and intermediate shaft 18.

Bushing 11 has a depression 7 on its outer side, and is accommodated inthe cylindrical, preferably non-graduated accommodation areas of housingparts 12, 14. Preferably, the accommodation areas are produced as a borehole.

Consequently, depression 7, together with the wall of the accommodationarea of first housing part 12, delimits an annular spatial area in whichadhesive may be introduced. Thus, the adhesive then ensures arotatably-fixed connection between first housing part 12 and bushing 11.

In addition, bushing 11 has on its outer surface, thus, on the outersurface of outer sleeve section 22, a first axial part which is realizedas insertion-fit area 1 and which facilitates the insertion of bushing11 into the accommodation area, and an axial part adjacent to it whichis effective as interference-fit area 2, so that a high static frictionis obtained.

Preferably, the accommodation area of housing part 12 is additionallyshrunk thermally onto the bushing. To that end, a temperature differenceis provided between the bushing and housing part 12 during the joiningprocess.

In the same way, the bushing also has an insertion-fit area and aninterference-fit area which are effective upon joining with secondhousing part 14.

Bushing 11 has an inner sleeve section 21 and an outer sleeve section22, inner sleeve section 21 accommodating the respective outer rings ofbearings 8, 10, and outer sleeve section 22 contacting the accommodationareas of housing parts 12, 14.

In the radial clearance area between the two sleeve sections 21, 22,radially extending, spoke-like support ribs 4 are situated, so that anaxial through-opening 3 is present between each two next-adjacentsupport ribs in the circumferential direction. In this way, oil is ableto be passed through from the axially front to the axially rear side ofbushing 11.

Support ribs 4, outer sleeve section 22 and inner sleeve section 21 arepreferably realized in one piece.

Bushing 11 is preferably made of steel or a metal such as aluminum.

In a further exemplary embodiment of the present invention, instead oftapered roller bearings 8, 10 shown, disposed in O-configuration ortandem configuration, other bearings such as ball roller bearings areused.

LIST OF REFERENCE CHARACTERS

-   1. Insertion-fit area-   2. Interference-fit area-   3. Opening, through-hole for oil exchange-   4. Support rib-   5. Line of symmetry-   6. Bearing housing-   7. Depression to form a spatial area for adhesive bonding as a    safeguard against twisting-   8. Bearing-   9. Bevel pinion-   10. Bearing-   11. Bushing-   12. First housing part-   13. Bevel-gear wheel-   14. Second housing part-   16. Gear wheel-   17. Shaft, particularly input shaft, especially rotor of an electric    motor-   18. Intermediate shaft-   19. Retaining ring-   20. Gear wheel-   21. Inner sleeve section-   22. Outer sleeve section

What is claimed is:
 1. A gear unit, comprising: a housing including afirst housing part and a second housing part; a bushing; and twobearings accommodated in the bushing and adapted to rotatably support ashaft in the housing; wherein the bushing is at least partiallyinterference-fit to the first housing part and at least partiallyslip-fit to the second housing part.
 2. The gear unit according to claim1, wherein the bushing centers the first housing part against the secondhousing part.
 3. The gear unit according to claim 1, wherein the bushingis at least partially slip-fit to the first housing part and at leastpartially interference-fit to the second housing part.
 4. The gear unitaccording to claim 1, wherein the bushing projects at least partiallyfrom the first housing part.
 5. The gear unit according to claim 4,wherein a portion of the bushing that project from the first housingpart is partially slip-fit to the second housing part and partiallyinterference-fit to the second housing part.
 6. The gear unit accordingto claim 1, wherein the bushing includes a first axial region arrangedas a slip-fit region and a second axial region arranged as aninterference-fit region.
 7. The gear unit according to claim 6, whereinthe slip-fit region is arranged at an axial end region of the bushingand the interference-fit region is located axially inward of theslip-fit region.
 8. The gear unit according to claim 1, wherein thebushing has an outer sleeve section that abuts against accommodationareas of the first and second housing parts.
 9. The gear unit accordingto claim 1, wherein the bushing has an inner sleeve section whichaccommodates a first bearing in a first axial part and a second bearingin a second axial part, wherein a crosspiece segment is disposed axiallybetween the first and second axial parts whose smallest radial distanceis less than a smallest radial distance of the first axial part or thesecond axial part.
 10. The gear unit according to claim 8, wherein thebushing has an inner sleeve section which accommodates a first bearingin a first axial part and a second bearing in a second axial part,wherein a crosspiece segment is disposed axially between the first andsecond axial parts whose smallest radial distance is less than asmallest radial distance of the first axial part or the second axialpart.
 11. The gear unit according to claim 10, wherein the inner sleevesection and the outer sleeve section are joined via support ribs thatare set apart from each other.
 12. The gear unit according to claim 11,wherein the support ribs are evenly spaced from each other in acircumferential direction.
 13. The gear unit according to claim 1,wherein the bearings are tapered roller bearings in an O-configuration,an X-configuration, and/or a tandem configuration.
 14. The gear unitaccording to claim 1, wherein: the intermediate shaft is joined inrotatably fixed manner to a first toothing part or has a correspondingtoothing section, so that a first axial bearing is bounded axially bythe toothing part or the toothing section; and on an opposite axial sideof the bushing, a further toothing part is joined in a rotatably fixedmanner to the intermediate shaft and bounds the other bearing axially.15. The gear unit according to claim 14, wherein the further toothingpart is bounded axially by a retaining ring.
 16. The gear unit accordingto claim 1, wherein the bushing is pressed into an accommodation area ofthe first housing part and into an accommodation area, situatedcoaxially relative to the accommodation area of the first part, of thesecond housing part.
 17. The gear unit according to claim 1, wherein thefirst and second housing parts are imperviously joined.
 18. The gearunit according to claim 16, wherein an annular spatial area adapted toreceive adhesive is located between one of the housing parts and thebushing.
 19. The gear unit according to claim 18, wherein the spatialarea is delimited by a depression in the bushing and by an accommodationarea of one of the first housing part and the second housing part forthe bushing.
 20. The gear unit according to claim 18, wherein anadhesive is provided in the annular spatial area and rotatably fixes theone of the housing parts and the bushing.